Inspirator



Feb. 8, 1966 F. T. ANDERSON 3,233,654

INSPIRATOR Filed Nov. 20, 1965 2 Sheets-Sheel l J aa Q ,40,42 6M) J 26 l if i 28| 36 a4 /40 fof WNS: 541 ai? if 1 M.. 42 M l 78 a :Q21 V24, -59- BY M ATTO/P/VYS Feb. 8, 1966 F. T. ANDERsoN 3,233,654

INSPIRATOR Filed Nov. 2 0, 1962 2 Sl'xeets-Sheel 2 INVENTOR.

United States Patent Yi() 3,233,654 INSPIRATOR Fred T. Anderson, South Lyon, Mich., assigner of forty percent to Garnard W. Niece, South Lyon, Mich., and twenty percent to Ciifton il). Hill, Northville, Mich. Fiied Nov. 20, 1963, Ser. No. 325,013

9 Claims. (Cl. 158--118) This invention relates to an inspirator for a gasburner.

The objects of 'this invention are to provide an air-gas inspirator that is compact and versatile; that is constructed simply and economically; and that effectively inspirates and thoroughly mixes air with a stream of combustible `gas in a short throat between air and gas intakes and lburner ports where combustion occurs.

In the drawings:

FIG. l is a View showing a tubular sheet metal gas burner mounted in a gas heating device and equipped with the inspirator of the present invention.

`FIG. 2 is an enlarged vertical section of the inspirator and an end Aportion of the tubular burner shown in FIG. l to illustrate the inspiration and mixing action achieved by .the present invention.

FIG. 3 is an end view of the inspirator taken from 'the left of FIG. 2.

FIG. 4 is a sectional view along line 4--4 in FIG. 2.

FIG. 5 is a sectional View along line 5-5 vin FIG. 2.

FIG. 6 is an enlarged fragmentary sectional view illustrating the configuration of gas inlets positioned around the periphery of the inspirator.

FIG. 7 is an enlarged sectional view illustrating the longitudinal cross-section of a single inlet.

FIG. 8 is an enlarged perspective View of a single inlet.

FIGf9 is a fragmentary sectional View looking into the orifice of a single inlet.

FIG. l is a sectional View illustrating the formation of a single inlet with a .lancing tool.

FIG. l1 is a fragmentary sectional view along line 11-11 in FIG. l0.

For purposes of illustration and not by Way of limitation, FIG. l shows a gas heating `device khaving an outer housing 2% enclosing an inner casing 22 which defines a chamber arranged to be heated by a gas burner `tube 24. Tube 24 is mounted on housing 2t) by a pair of brackets 26. Tube 24 may be formed of sheet metal and is open at its inlet end as alt 28 and closed at its other end as at 30. Air from vents.32 in housing 20 and gas 'froma pipe 34 are mixed and fedto tube 24 by a two stage inspirator 36 telescopically mounted on tube 24 adjacent end 2ti by a bracket 33. Tube 24 has burner ports 40 which may be formed by the space between tabs 42 which are struck inwardly `alon g tube 24.

As shown in FIGS. 2 thru 9, inspirator 36 comprises a short, open-ended tube `44 which defines a first stage mixing chamber 46 having a primary air intake vport 48 at one end, an air-gas youtlet port Sti at 'its other end, `and four gas inlet ports 52 intermediate its ends. Tube 44 has its end portion 54 adjacent outlet port 5d disposed concentrically within and spaced radially from tube 24 to de'line a primary air intake 56 in the space therebetween. The terminal portion of tube 24 adjacent tube 44 defines a second stage mixing chamber 59 between port 54) and ports 4t). Tube 44 has a cross-sectional area approximately one-half the cross-sectional area of tube 24. A gas inlet fitting S is mounted on tube 44 adjacent port 48 and has a bored nipple 6i) for coupling pipe 34 to fitting 58. Fitting S8 has an internal annular groove 62 which communicates with ports 52 and the bore of nipple 60 to supply gas to chamber 46. Bracket 38 has a ring-shaped portion 68 clamped on tube 24 by a nut and bolt 70 and also has a pair of dog legs 72 extending `forms the trough-like indentations 82.

Patented Feb. 8, 196:6

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downwardly and rearwardly as viewed in FIGS. l and 2, each leg 72 having an inwardly bent, terminal tab 74 secured to tting 53 by a screw 76. Air intake through port 48 is controlled by a shutter Valve. 78 adjustably mounted to `fitting 58 by one of the screws 76.

- Ports 52 are equally spaced circumferentially about the inner periphery of tube 44 (FIG. 5). Each port 52 comprises a generally trough-shaped indentation 82 struck inwardly from the wall of tube 44. Each indentation 82 tapers inwardly toward port Si) (FIG. 2) and forms a restricted orifice 84 opening generally axially of chamber 46 in a direction toward outlet port 50.. Additionally, each indentation S2 is set at a slight angle, approximately ten (1G) degrees axially to the burner, as illustrated by the broken line .in FIG. 6, to impart to the stream of gas issuing 'from each orifice @4, a generally helical motion `about the longitudinal axis of chamber 46 (FIG. 2) in a direction toward outlet port Sti. Since each indentation 82 *tapers radially inward, a 'stream of gas issuing from orifice $4 will also be directed slightly radially inward toward the axis 'of chamber 46 (FIG. 2).

Ports S2 may be advantageously formed by slidably vsupporting tube 44 on a suitable arbor 90 and using a 'tool of the type illustrated at 92 (FIG. l0). At its lower end, tool 92 is fashioned with a pair of angularly related faces 94 providing a Wedge formation which inclines upwardly away from a forward cutting edge 96 of the tool 92. When tool 92 is driven downwardly into the wall of tube 44, edge 96 lances the tube circumferentially as at 9S and the wedge formation provided by faces 94 Although the orifice formed by lancing tool 92 is close to the round shape illustrated in FIGS. 5, 8 and l0 and will function satisfactorily, preferably oriiice 84 is brought to nished 'size and shape `by-dril'ling as indicated in FIG. 8 -by a slight amount of material removed at 106.

In operation of the device described hereinabove, gas is fed from pipe 34, nipple 6u and groove 62 to ports S2 and `issues Afrom orifice 34 into chamber 46 as high velocity streams illustrated generally yby arrows 104 (FIG. 2). The high velocity streams of gas draw primary air (illustrated by arrows through port 48 into chamber V46 ywhere it is thoroughly mixed with the gas. Because each orifice `84 (FIGS. 5 6) imparts a generally .helical motion to the stream of gas issuing therefrom, turbulence `and swirling of the `gas provides `etiicient and effective mixing. As the air-gas mixture in chamber 46 exhausts Vthrough port Sli into the larger diameter `burner tube 24, additional primary air (illustrated by arrows 1%) 'is drawn `through the annular intake port 56 and mixed in chamber 59 before the airgas rnixture exhausts through :ports 40 where it ignites.

By using the two-stage inspirator described hereinabove 4extremely eflicient and `effective mixing is achieved `with 'a `very 'high percentage of primary Aair for the mixture Aissuing from `ports 4b. In practice, this is evidenced by a hard, deep -blue flame and additionally, where multiple rows of burner ports are used, there is no tendency of the outside rows to blanket or starve the inside rows of suflicient secondary air. T-he quantity of primary air for the first stage mixing in chamber 46 may be controlled by varying the angular position of shutter valve 78 while the quantity of primary air for the second stage mixing in chamber 59 may be varied by loosening screw 7i) and moving tube 44 axially back and forth at the end of burner tube 24. In numerous applications, only a single stage is required in which case the burner tube 24 may be used to form the mixing chamber corresponding to chamber 46.

One of the primary advantages of the inspirator disclosed hereinabove, whether single stagel or two stage, is

that for most applications the swirling motion of the gas streams achieves effective and eicient mixing in a very short throat, that is, the axial distance from orifices 84 to the burner port closest to orifices 84 that is necessary to mix the air and gas sutiiciently for complete and proper burning. By way of example, with a single-stage inspirator, it has been found that etiective mixing due to the swirling motion can be achieved within approximately one and one-half inches in a one-inch diameter tube for certain applications. Generally, in a single-stage inspirator, a mixing chamber or throat having a length of approximately one and one-half times the diameter of the tube can achieve effective mixing, while in a two-stage inspirator, a mixing chamber or throat having a length of approximately two times the diameter of the tube can achieve effective mixing. This short throat substantially reduces the length of the combined burner and inspirator or the height where the inspirator must be located below the burner tube. Another advantage achieved by the two-stage inspirator and to some extent by a single stage inspirator is that the primary air remains cooler than in conventional inspirators since the air is inspirated directly into the burner tube. The cooler air-gas mixture keeps the entire burner cooler than a similar burner having a conventional inspirator. Overheated burner tubes have poor air injection due to expansion and more carbon deposits on the burner. Although the inspirator disclosed hereinabove is particularly adapted for use with a tubulartype burner, it has been found that it works Well with numerous types of conventional burners.

I claim:

1. The combination for inspirating air into a stream of combustible gas to form an air-gas mixture for a gas burner comprising a sheet metal tube forming a mixture chamber open at one end to serve as an air inlet, the other end of said chamber being open to serve as an outlet for said mixture, means positioned intermediate the ends of said tube forming a peripheral passageway exterior of said chamber, said passageway having an inlet adapted to be connected to a source of combustible gas, a plurality 0f inwardly lanced indentations spaced circumferentially around the periphery of said tube and communicating with said passageway exteriorly of said tube, each of said indentations having an opening therein facing with components of direction peripherally and axially of said chamber to impart to streams of gas issuing from said openings a generally helical swirling motion along the axis of said chamber toward said outlet.

2. The combination for inspirating air into a stream o of combustible gas to form an air-gas mixture for a gas burner comprising iirst and second sheet metal tubes having nested terminal portions in spaced concentric relation to provide an air inlet therebetween, the inner of said nested tubes extending longitudinally outwardly from the terminal portion of the outer tube, said inner tube being open at its end remote from said outer tube to serve as a second air inlet, means on said inner tube adjacent said second air inlet forming a peripheral passageway exteriorly of saidV chamber, said passageway having an inlet adapted to be connected to a source of combustible gas, a plurality of inwardly lanced indentations spaced circumferentially around the periphery of said inner tube adjacent said second air inlet and communicating with said passageway exteriorly of said tube, each of said indentations having an opening therein facing with components of direction peripherally and axially of said inner tube.

3. The combination set forth in claim 2 wherein means are provided whereby said terminal portions of said tubes are telescopic to adjust the quantity of air entering said second air inlet.

4. The combination set forth in claim 3 wherein the other of said tubes has openings therein spaced longitudinally along said outer tube to form burner ports for said burner.

5. The combination set forth in claim 3 further comprising a bracket interconnecting said inner tube and said outer tube to adjustably support said inner tube on said outer tube, said bracket being xedly mounted on one of said tubes and releasably mounted on the other of said tubes whereby said bracket may be released from the other of said tubes and thencsting of said terminal portions of said tubes may be telescopically adjusted to vary said first air inlet.

6. The combination set forth in claim 5 wherein said bracket comprises a ring-shaped clamp mounted on said outer tube and a pair of legs, one end of each of said legs being integral with said clamp, the other end of each of said legs extending longitudinally of said outer tube in a direction away from the terminal portion of said outer tube and being fixedly mounted on said passageway forming means.

'7. The combination set forth in claim 1 wherein said indentations are trough-shaped and are formed by driving a wedge-shaped lancing tool radially inward from the exterior of said tube.

8. The combination set forth in claim 2 wherein said indentations are trough-shaped and are formed by driving a wedged-shaped lancing tool radiall;I inwardly from the exterior of said tube.

9. The combination set forth in claim Z wherein said outer tube has openings spaced longitudinally therealong to form burner ports for said burner, said burner having a circular cross section, said indentation openings being spaced from the closest one of said burner ports a distance on the order of twice the diameter of said outer tube.

Reierences Cited by the Examiner UNITED STATES PATENTS 914,193 3/1909 Schumacher 158-118 X 1,006,324 10/1911 Werner 158-118 X 2,222,822 l1/1940 Nordensson 158-118 X 2,728,384 12/1955 Anderson 158-116 X 2,980,104 4/1961 Patrick et al. 158-114 X JAMES W. WESTHAVER Primary Examiner. FREDERICK L. MATTESON, JR., Examiner. 

1. THE COMBINATION FOR INSPIRATING AIR INTO A STREAM OF COMBUSTIBLE GAS TO FORM AN AIR-GAS MIXTURE FOR A GAS BURNER COMPRISING A SHEET METAL TUBE FORMING A MIXTURE CHAMBER OPEN AT ONE END TO SERVE AS AN AIR INLET, THE OTHER END OF SAID CHAMBER BEING OPEN TO SERVE AS AN OUTLET FOR SAID MIXTURE, MEANS POSITIONED INTERMEDIATE THE ENDS OF SAID TUBE FORMING A PERIPHERAL PASSAGEWAY EXTERIOR OF SAID CHAMBER, SAID PASSAGEWAY HAVING AN INLET ADAPTED TO BE CONNECTED TO A SOURCE OF COMBUSTIBLE GAS, A PLURALITY OF INWARDLY LANCED INDENTATIONS SPACED CIRCUMFERENTIALLY AROUND THE PERIPHERY OF SAID TUBE AND COMMUNICATING WITH SAID PASSAGEWAY EXTERIORLY OF SAID TUBE, EACH OF SAID INDENTATIONS HAVING AN OPENING THEREIN FACING EITH COMPONENTS OF DIRECTION PERIPHERALLY AND AXIALLY OF SAID CHAMBER TO IMPART TO STREAMS OF GAS ISSUING FROM SAID OPENINGS A GENERALLY HELICAL SWIRLING MOTION ALONG THE AXIS OF SAID CHAMBER TOWARD SAID OUTLET. 